Ultrasensitivity for Treatment Management
The Aptima HCV Quant Dx assay’s Limit of Detection (LoD) is 3.9 IU/mL in plasma and 3.4 IU/mL in serum.
(All tables and figures in this section can be found in the Aptima HCV Quant Dx Assay Package Insert.)
LoD of the Aptima HCV Quant Dx Assay Using the WHO 2nd International Standard
The LoD of the assay is defined as the concentration of HCV RNA that is detected at 95% or greater probability according to CLSI EP17-A2.18
The LoD was determined by testing panels of the WHO 2nd International Standard for Hepatitis C Virus RNA (NIBSC 96/798 genotype 1) diluted in HCV negative human EDTA plasma and serum. Each dilution had 36 replicates which were tested with each of 3 reagent lots for a minimum of 108 replicates per dilution. Probit analysis was performed to generate the predicted detection limits. The LoD values are the results from the reagent lot with the highest predicted detection limit. The 95% LoD for the Aptima HCV Quant Dx assay using the WHO 2nd International Standard is 3.9 IU/mL for plasma and 3.4 IU/mL for serum.
LoD Across HCV Genotypes 1-6
Lower Limit of Quantitation (LLoQ)
The LLoQ of the Aptima HCV Quant Dx assay is 10 IU/mL.
Determination of LLoQ Across Genotypes in Plasma
Determination of LLoQ Across Genotypes in Serum
Confidence in Performance Across a Broad Linear Range
The linear range was established by testing panels of HCV Armored RNA (aRNA) diluted in HCV negative human plasma and serum according to CLSI EP06-A.19. Panels ranged in concentration from 1.0 log10 IU/mL to 8.2 log10 IU/mL. The Aptima HCV Quant Dx assay demonstrated linearity across the range tested, with an upper limit of quantitation (ULoQ) of 8.0 log10 IU/mL.
Linearity in Plasma and Serum
Linear Range and Linearity (Plasma)
Linear Range and Linearity (Serum)
The Aptima HCV Quant Dx assay precision panel was built by diluting HCV-positive clinical plasma and HCV aRNA into HCV-negative clinical plasma (the two highest panel members were aRNA). Seven positive panel members spanned the range of the assay (1.86 log10 IU/mL to 7.68 log10 IU/mL), and were tested in 3 replicates per run by 1 operator, using 1 pilot lot of reagents on 1 Panther system over 21 test days, 2 runs a day. Total variability was ≤ 0.14 across all panel members, primarily due to intra-run variability (i.e., random error).
Precision of the Aptima HCV Quant Dx Assay
Sample Dilution Using Aptima Specimen Diluent
To assess the detection accuracy of HCV RNA in samples diluted with Aptima Specimen Diluent plasma or serum, 5 naturally infected plasma specimens and 5 naturally infected serum specimens, along with 10 specimens each of HCV negative plasma and serum spiked with HCV aRNA targeting above the ULoQ, 8 log10 IU/mL at 8.30 log10 IU/mL were tested in triplicate. A 1:100 dilution was performed with 1 part sample and 99 parts Aptima Specimen Diluent just prior to testing. Testing was performed using 1 lot of assay reagents on 1 Panther system with 2 Aptima Specimen Diluent lots. The difference between the neat and diluted test results was calculated for each sample.
Plasma Specimen 1:100 Dilution Matrix Comparison Summary of Log10 IU/mL
Serum Specimen 1:100 Dilution Matrix Comparison Summary of Log10 IU/mL